Since the fall of the Soviet Union, injection drug abuse has become epidemic in Russia and the Ukraine. Beginning in 1995, a second epidemic, HIV-1 infection, has swept through Russia and the Ukraine. In the past six years, HIV-1 infections have increased from fewer than 2,000 to more than half a million in the two countries. This HIV-1 epidemic is unique in that almost all of the HIV-1 infections have occurred within communities of drug injectors. One feature of drug injection that is different between these countries and the rest of the world is the common use of homemade liquid opiate and amphetamine preparations. We seek to investigate the link between these two phenomena through an interdisciplinary study that investigates the virological and social consequences of liquid drug use. Because blood is sometimes used during the manufacture of liquid opiates, transmission of HIV-1 may be rampant if the virus survives the manufacturing process. We propose to test this possibility in the lab both simulating the drug preparations practices observed by field ethnographers during liquid drug manufacture and testing drug preparations themselves. In addition, we propose to investigate the extent to which the communal nature of liquid drug manufacture results in drug preparation and injection practices which place injectors in Russia and the Ukraine at great risk for HIV-1 infection. This study will be carried out by a multinational, multidisciplinary team of researchers building on the strength of a NIH-funded AIDS International Training and Research Program linking researchers in St. Petersburg to their colleagues at Yale University. With the addition of an international expert on liquid drug manufacturing and injection practices, this team is uniquely positioned to investigate the linkages between liquid drug use and the HIV-1 epidemic in Russian and Ukrainian drug injectors.